The present invention relates generally to a portable solid-fuel thermosyphon system, and more particularly to a thermosyphon system for use by outdoor enthusiasts, such as campers, hunters, and others, for instance, soldiers or missionaries, located remote from a conventional hot water source.
The concepts of a conventional solid-fuel thermosyphon which heats water by gravity flow is disclosed in Larry Gay's book entitled, Heating the Home Water Supply (Garden Way Publishing, 1983). Such of a conventional thermosyphon water heating system typically is constructed at a permanent location, i.e., it is not portable.
Such a conventional gravity flow system operates on the premise that, as water is heated, it becomes less dense and flows upwardly. This closed loop water heating system has a tank coupled to a heat exchanger coil, which is placed within a stove. The tank has a cold water outlet near the bottom of the tank and a hot water inlet near the top of the tank. A piping system connects the cold water outlet to the coil, and then conducts water from the coil through a riser portion of the piping to the tank hot water inlet. This flowing action then draws cold water from the lower portion of the tank into the heat exchanger coil.
Unfortunately, in conventional closed loop systems, the only usable hot water that may be extracted from the tank is that located above the hot water inlet. Otherwise, if the water level in the tank drops below the hot water inlet, the syphon action will cease, resulting in system failure.
Regarding portable water heating systems, such as those used for camping, outdoor enthusiasts typically obtain hot water by heating water in an open container. Unfortunately, this method takes time and does not provide hot water on demand.
Others have sought to overcome these shortcomings and provide hot water for outdoor enthusiasts. These earlier systems primarily use an open flame with a coil heat exchanger. For example, such a system is disclosed in U.S. Pat. No. 3,687,128. Typically, the open flame is generated from a gas-fired source, which requires a pressurized gas supply. Furthermore, for adequate circulation of the water through the heat exchanger, these devices also require the water storage tanks to be a pressurized vessel. Pressurized vessels and a pressurized gas supply are heavy, bulky and thus, burdensome to transport. Moreover, for extended stays at remote locations, maintaining a pressurized gas supply may not be feasible.
Other sources of hot water are generated using solar collectors, with one typical system being shown in U.S. Pat. No. 4,520,793. Unfortunately, solar water heaters depend upon passive solar energy collection, and their efficiency is severely affected by poor environmental conditions, e.g., cloud covered days, evenings, cold weather, etc. While solar powered thermosyphon systems have been effectively used in home water heating systems using home solar collectors, the size of an efficient solar panel prohibits such heating systems from being portable. Moreover, these home solar collectors typically require a considerable amount of time to heat the water to an adequate temperature for use.
While these earlier devices may be satisfactory for the particular purposes and installations for which they were intended, to the best of the inventors knowledge, there has not been a portable, compact hot water heating system available for use by outdoor enthusiasts and the like, which does not require the use of pressurized fuel and/or a pressurized water tank.
Thus, a need exists for a portable water heating system, and more particularly a solid fuel, non-pressurized, portable water heater, that can provide hot water on demand using a campfire or the like as a heat source, which is directed toward overcoming, and not susceptible to, the above limitations and disadvantages.